Alloy



Patented Dec. 23, 1941 Reginald s.' Dean,

Salt Lake City, Utah, assignor to Chicago Development Company, Chicago,111., a corporation of Illinois No Drawing. Application June 12, 1940,Serial No. 340,135

4 Claims. (Cl. 75-178) This invention relates to alloys of copper, zincand manganese and, in particular, is concerned with such alloys for diecasting purposes.

The alloys of the present invention contain relatively high proportionsof zinc, of the order of 60% to 95% zinc, the balance comprising fromabout 2% to about 30% copper, and from about 5% to about 38% manganese.Small proportions of other alloying constituents may, in certain cases,be utilized where special characeristics are desired, but, in general,the alloys contain substantially only zinc, copper and manganese, suchother elements as are present being introduced only as impurities. Itshould be pointed out at the outset, however, that, for best results,the manganese employed should be electrolytic manganese or other highlypure manganese containmg. preferably, not more than 0.1% of other metalsas impurities, and the copper and zinc should also be of highly puregrade, preferably electrolytic.

Although many of the alloys of the present invention have little orsubstantially no ductility, nevertheless they possess sufiicientstrength to make them of marked value for die casting or other castingsfor parts which are not subjected to great mechanical stress. Ingeneral, the alloys of the present invention possess the advantage, overthe zinc-copper-manganese alloys heretotore suggested for die castingpurposes, in that they are more fluid and can be cast into moreintricate shapes while maintaining accuracy of dimensions. Furthermore,they possess an excellent finish, as cast, are readily machinable andare highly resistant to corrosion.

The alloys of the present invention may be produced in accordance withvarious procedures,

about 0.1% of metallic impurities, may be used in the production of thealloys in accordance with the present invention, for the best results,as previously noted, electrolytic manganese should be used, both becauseof the relative read- 2 mess with which the alloys are made in accordbutone suitable and dependable method comprises preparing an alloy of zincand copper and subsequently adding the manganese in the form of a fairlyfine powder. It has been found that if the substantially molten mixtureis stirred at a temperature slightly below the boiling point of zinc, ahomogeneous alloy is produced. An alternative, and also satisfactorymethod, comprises initially melting the manganese, preferably in a highfrequency induction furnace, alloying the same with the copper, and thenadding the zinc at a temperature slightly above the melting point of themanganese-copper alloy. Although, in this latter method, there is aslight volatilization of the zinc, the amount volatilized is so small asto--be disregarded.

While, as previously stated, any manganese of ance with the presentinvention and also because of the especially satisfactory properties ofthe resulting alloys. i

y The following are illustrative examples of alloys which may be made inaccordance with the present invention. It willbe understood that theproportions of the alloying constituents may vary, Within the range setforth hereinabove, and other (changes may be made without departing fromthe spirit of the invention as pointed out in the appended claims:

Example! Parts Electrolyti zinc 85 Electrolytic manganese 10Electrolytic copper 5 Example 2 Parts Electrolytic zinc l Electrolyticmanganese 10 Electrolytic copper "L- 10 Example 3 f Parts- Electrolyticzinc 86" Electrolytic manganese 9 Electrolytic copper u r 5 Aparticularly preferred range of the alloying constituents, fallingwithinthe broader range set forth hereinabove, is from 75% to zinc. from5% to 15% copper, and from 8% to 20% manganese, the total of thealloying constituents comprising substantially 100%;

What I claim as new and desire to protect by Letters Patent of theUnited States is:

1. An alloy suitable for the preparation of die castings having goodfinish, resistance to atmospheric corrosion, and ease of machinability,said alloy containingfrom in excess of 75% up to about zinc, 2% to 30%copper, and 5% to 38% manganese, the total of said alloying constituentsamounting to substantially 2. An alloy suitable for the preparation ofdie castings having good finish, resistanceto atmospheric corrosion, and,eose of machinability,

high purity, that is, containing not more than 55 said alloy containingfrom in excess of 75% up to about 95% 'electrolytic zinc, from 2% to 30%electrolytic vcopper, a}? from 5% to 38% electrolytic manganese havinz apurity of at least to! of said alloyin: constituents nmountinl to 99.9%,the total said alloying constituents substantially 100%.

amountin to substantially 109%. 4. A casting alloy containing about 85%line. 3. A die casting consisting 01 an alloy conabout 5% copper, andabout substantially taining from in excess of 75% up to about 85% 5 puremanganese.

zinc, from 5% to copper, and from 8% to REGINALD S. DEAN.

% of a substantially pure manganese, the to-

